movable bridge

Transporter bridge

A transporter bridge (also ferry bridge or aerial transfer bridge) is a type of movable bridge that carries a segment of roadway across a river. The gondola is slung from a tall span by wires or a metal frame. The design has been used to cross navigable rivers or other bodies of water, where there is a requirement for ship traffic to be able to pass. This has been a rare type of bridge, with fewer than two dozen built. Just eight, plus one converted into a lift bridge, continue to be used today.
The first transporter bridge, Vizcaya Bridge was built in Portugalete, Spain in 1893. The design from Alberto Palacio inspired others to attempt similar structures. The idea found use where it was seen as impractical to build the long approach ramps that would be required to reach a high span, and in places where ferries are not easily able to cross. Because transporter bridges can carry only a limited load, the idea was little used with the rise of the automobile.

The first French bridge was destroyed by the French army to slow down German troops in World War II.

Transporter bridges were most popular in France, where five were erected and another was partially completed. However, the United Kingdom has the largest number of transporter bridges today with four, though one is not currently in use.

The Newport Transporter Bridge was built in 1906 across the River Usk in Newport. Because the river banks are very low at the crossing point (a few miles south of the city centre) a traditional bridge would need a very long approach ramp and a ferry could not be used at low tide. The Newport bridge was a Ferdinand Arnodin design.

In the United States, two such bridges were built. The first was the Aerial Bridge built in Duluth, Minnesota in 1905, although the city had originally planned to build a vertical lift bridge at the site. The transporter design was used for about 25 years before the structure was reconfigured to lift a central span in 1930.

The second American transporter bridge was different from other designs and partially resembled gondola lifts used in mountainous regions. The Sky Ride was part of the 1933–34 Chicago World's Fair ("Century of Progress"), it was taken down after standing for just two years. However, it was the longest bridge of this type ever built at the time.

Two transporter bridges exist in Germany, in Rendsburg and Osten (Oste). One unique example is the bridge at Rendsburg, which is actually two bridges in one. A railroad link crosses high above on the top span, and the suspended ferry carries traffic on the valley floor.

The Soviets built the longest recorded transporter bridge, two decades later, in Stalingrad (now Volgograd).